From 189070cf2ced2cb2bb7c7f226d81237c56875564 Mon Sep 17 00:00:00 2001
From: Sauyon Lee <sauyon@github.com>
Date: Tue, 17 Aug 2021 09:42:26 -0700
Subject: [PATCH] Add support for go:build style constraints

This doesn't account for the new syntax, but there was no syntax
parsing in the old version anyway, and the only user doesn't currently
care about semantics
---
 ql/src/semmle/go/Comments.qll | 14 ++++++++++----
 ql/src/semmle/go/Files.qll    |  2 ++
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/ql/src/semmle/go/Comments.qll b/ql/src/semmle/go/Comments.qll
index 2a765c5e972..e072c0cb7ca 100644
--- a/ql/src/semmle/go/Comments.qll
+++ b/ql/src/semmle/go/Comments.qll
@@ -189,7 +189,7 @@ private Comment getInitialComment(File f, int i) {
 }
 
 /**
- * A build constraint comment of the form `// +build ...`.
+ * A build constraint comment of the form `// +build ...` or `//go:build ...`.
  *
  * Examples:
  *
@@ -203,17 +203,23 @@ class BuildConstraintComment extends LineComment {
     // a line comment preceding the package declaration, itself only preceded by
     // line comments
     exists(File f, int i |
+      // correctness of the placement of the build constraint is not checked here;
+      // this is more lax than the actual rules for build constraints
       this = getInitialComment(f, i) and
       not getInitialComment(f, [0 .. i - 1]) instanceof BlockComment
     ) and
-    // comment text starts with `+build`
-    getText().regexpMatch("\\s*\\+build.*")
+    (
+      // comment text starts with `+build` or `go:build`
+      this.getText().regexpMatch("\\s*\\+build.*")
+      or
+      this.getText().regexpMatch("\\s*go:build.*")
+    )
   }
 
   override string getAPrimaryQlClass() { result = "BuildConstraintComment" }
 
   /** Gets the body of this build constraint. */
-  string getConstraintBody() { result = getText().splitAt("+build ", 1) }
+  string getConstraintBody() { result = getText().splitAt("build ", 1) }
 
   /** Gets a disjunct of this build constraint. */
   string getADisjunct() { result = getConstraintBody().splitAt(" ") }
diff --git a/ql/src/semmle/go/Files.qll b/ql/src/semmle/go/Files.qll
index ed27c6b557b..92981b74711 100644
--- a/ql/src/semmle/go/Files.qll
+++ b/ql/src/semmle/go/Files.qll
@@ -222,6 +222,8 @@ class ExtractedOrExternalFile extends Container, @file, Documentable, ExprParent
     exists(BuildConstraintComment bcc | this = bcc.getFile() |
       forex(string disjunct | disjunct = bcc.getADisjunct() |
         disjunct.splitAt(",").(Architecture).getBitSize() = bitSize
+        or
+        disjunct.splitAt("/").(Architecture).getBitSize() = bitSize
       )
     )
   }